3.2.3 Brain scans Flashcards
What does a CAT scan stand for ?
Computerised Axial Tomography
What does a CAT scan do ?
Takes images of the brain
How does a CAT scan work ?
Multiple X ray beams are passed around the head from different angles to gather information which is interpreted by a computer
What does a CAT scan show ?
Brain structure
What are strengths of CAT scans ?
- Quick to conduct, accurate detail of brain structure
- Guide clinicians in decision making
- Fast & efficient
- Less risky to exploratory surgery
What are weaknesses of CAT scans ?
- Risk to patients
- Pregnant women cannot have scan
What does a PET scan stand for ?
Positron Emission Tomography
How does a PET scan work ?
- Inject FDG
- Radioactive atom attached to glucose
- Tracer absorbs into bloodstream
- Brain activity encouraged
- Radioactive atom breakdown into emitting positrons
- Gamma rays produced
What does a PET scan show ?
Shows brain activity, warmer colours = high activity, colder colours = low activity
What are strengths of PET scans ?
- Detects damage
- Researchers see where problems exist
- Predict issues patients may face
- Low risk
What are weaknesses of PET scans ?
- More invasive
- Unclear if long term effects
What does an fMRI scan stand for ?
Functional Magnetic Resonance Imaging
How does an fMRI scan work ?
- Head placed in large, powerful electromagnet
- Nuclei in hydrogen molecules in water align with direction of magnetic field
- Neural activity increases, blood flow increases in active areas to seep up with demand for oxygen
- Oxygen carried to neutrons in hamaeglobin
- Oxygenated hamaeglobin repels magnetic field (diamagnetic)
- Deoxygenated hamaeglobin follows magnetic field (paramagnetic)
How does an fMRI scan show ?
Scanner detects changes to create image, sent to computer map of activation showing changing levels of neural activity in different areas
What are strengths of fMRI scans ?
Non-invasive
